| 摘要 |
401,293. Control of D.C. motors. RAMSDEN, H. K., 26, Ashlands, Ashton-on- Mersey, COLLIS, W. B. G., The Rocklands, Clent, Worcestershire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. May 4, 1932, Nos. 12882 and 17317. [Class 38 (iii).] In a series parallel control system, the field windings F1, F2, of the motors A1, A2, are arranged to be automatically shunted by diverter resistances S1, S2, under the control of electrically operated switches FS1, FS2, the coils OCFS1, OCFS2, of which are so connected in the motor circuits as only to be effectively energised when the motors are motoring in parallel. The coils may be connected as shown between the supply T and a switch M which is closed only in the parallel positions. Alternatively the coils may be connected across the main supply in series with the normally open contacts of a relay, the coil of which is connected between the supply and the switch M. In a modification the coils OCFS1, OCFS2, or the coil of a relay controlling these coils may be connected across the switch JR open only in the parallel positions. In order to prevent the switches FS1, FS2, from closing during parallel rheostatic braking when their controlling coils are connected across the switch JR the connection of the switch JR may be changed from the line to the field side of the motor armature A2 during braking, 20 that the controlling coil, energised only by the field voltage of the motor A2, is ineffective.
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